Simulation of teleseismic body waves, regional seismograms, and Rayleigh wave phase shifts using two-dimensional nonlinear models of explosion sources

1991 ◽  
pp. 239-252 ◽  
Author(s):  
Jeffry L. Stevens ◽  
Terrance G. Barker ◽  
Steven M. Day ◽  
Keith L. McLaughlin ◽  
Norton Rimer ◽  
...  
Keyword(s):  
Rayleigh Wave ◽  
Nonlinear Models ◽  
Phase Shifts ◽  
Body Waves ◽  
Two Dimensional ◽  
Wave Phase

TRANSMISSION AND REFLECTION OF RAYLEIGH WAVES AT CORNERS

Geophysics ◽  
1958 ◽  
Vol 23 (2) ◽  
pp. 253-266 ◽  
Author(s):  
J. Cl. de Bremaecker
Keyword(s):  
Surface Wave ◽  
Rayleigh Wave ◽  
Rayleigh Waves ◽  
Body Waves ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Reflection And Transmission ◽  
Two Dimensional Model ◽  
Model Seismology ◽  
Transmission And Reflection

The methods of two dimensional model seismology were used to investigate the phenomena occurring when a Rayleigh wave is incident upon a corner whose angle is comprised between 0° and 180°. The wave bends its path only for angles between 130° and 180°. For smaller angles large and abrupt variations in reflection and transmission occur; the wave travels to the extremity of the corner and never “cuts corners”; only about 50 percent of the energy of the indicent surface wave is preserved as such, the rest goes into body waves; for a 90° corner the proportion is about 23 percent in P and 26 percent in S, with sharply preferential angles of incidence. The percentages given were found for a “plate Poisson’s ratio” of 0.17.

Transmission and reflection of Rayleigh wave through a step

1977 ◽  
Vol 67 (5) ◽  
pp. 1277-1290
Author(s):  
L. Martel ◽  
M. Munasinghe ◽  
G. W. Farnell
Keyword(s):  
Rayleigh Wave ◽  
Phase Shifts ◽  
Body Waves ◽  
Reflected Wave ◽  
Homogeneous Half Space ◽  
Transmission And Reflection Coefficients ◽  
Group Delays ◽  
Seismic Models ◽  
Transmission And Reflection ◽  
Good Agreement

abstract The transmission and reflection of a Rayleigh wave through a step on a homogeneous half-space of Poisson's ratio σ = 0.253 have been investigated by a seismic models method. The experimental results show good agreement with numerical ones obtained by finite-difference calculations when the wave is incident onto a downward step. Phase shifts are given both for the upward and downward steps. The characteristics of the transmitted wave do not depend much on the direction of propagation but those of the reflected wave are clearly direction-dependent. In each case the transmission and reflection coefficients and phase shifts depend on the ratio of step height to wavelength. The group delays are calculated and they are positive or negative depending on the period. About 80 per cent of the incident energy is converted into body waves when the step is higher than 0.3 times the wavelength of the Rayleigh wave.

Two-dimensional linear and nonlinear wave propagation in a half-space

1999 ◽  
Vol 89 (4) ◽  
pp. 903-917 ◽  
Author(s):  
Heming Xu ◽  
Steven M. Day ◽  
Jean-Bernard H. Minster
Keyword(s):  
Wave Propagation ◽  
Free Surface ◽  
Phase Velocity ◽  
Rayleigh Wave ◽  
Half Space ◽  
Frequency Band ◽  
Pseudospectral Method ◽  
Two Dimensional ◽  
Wave Phase ◽  
Wave Phase Velocity

Abstract We examine a staggered pseudospectral method to solve a two-dimensional wave propagation problem with arbitrary nonlinear constitutive equations, and evaluate a general image method to simulate the traction-free boundary condition at the surface. This implementation employs a stress-velocity formulation and satisfies the free surface condition by explicitly setting surface shear stress to zero and making the normal stress antisymmetric about the free surface. Satisfactory agreement with analytical solutions to Lamb's problem is achieved for both vertical point force and explosion sources, and with perturbation solutions for nonlinearly elastic wave propagation within the domain of validity of such solutions. The Rayleigh wave, however, suffers much more severe numerical dispersion than do body waves. At four grids per wavelength, the relative error in the Rayleigh-wave phase velocity is 25 times greater than the corresponding error in the body-wave phase velocity. Thus for the Rayleigh wave, the pseudospectral method performs no better than a low-order finite difference method. A substantial merit of the image approach is that it does not assume any particular rheology, the method is readily applicable even when stresses are not analytically related to kinematic variables, as is the case for most nonlinear models. We use this scheme to investigate the response of a nonlinear half-space with endochronic rheology, which has been fit to quasi-static and dynamic observations. We find that harmonics of a monochromatic source are generated and evolve with epicentral range, and energy is transferred from low to higher frequencies for a broadband source. This energy redistribution characteristic of the propagation is strain-amplitude dependent, consistent with laboratory experiments. Compared with the linear response, the nonlinear response of an endochronic layer near the surface shows a deamplification effect in the intermediate-frequency band and an amplification effect in the higher-frequency band. The computational method, with modifications to accommodate realistic nonlinear soil characteristics, could be applied to estimate earthquake strong ground motions and path effects.

scholarly journals Direct estimation of the Rayleigh wave phase velocity in microtremors

2006 ◽  
Vol 33 (18) ◽  
pp. n/a-n/a ◽  
Author(s):  
Hidetaka Shiraishi ◽  
Tatsuro Matsuoka ◽  
Hiroshi Asanuma
Keyword(s):  
Phase Velocity ◽  
Rayleigh Wave ◽  
Direct Estimation ◽  
Wave Phase ◽  
Wave Phase Velocity ◽  
Rayleigh Wave Phase Velocity

Measurements of Rayleigh-wave phase velocities in Nevada: Implications for explosion sources and the Massachusetts Mountain earthquake

1982 ◽  
Vol 72 (4) ◽  
pp. 1329-1349
Author(s):  
H. J. Patton
Keyword(s):  
Rayleigh Wave ◽  
Rayleigh Waves ◽  
Moment Tensor ◽  
Test Site ◽  
P Wave ◽  
Stress Axis ◽  
Phase Velocities ◽  
Wave Phase ◽  
Single Station ◽  
Source Phase

abstract Single-station measurements of Rayleigh-wave phase velocity are obtained for paths between the Nevada Test Site and the Livermore broadband regional stations. Nuclear underground explosions detonated in Yucca Valley were the sources of the Rayleigh waves. The source phase φs required by the single-station method is calculated for an explosion source by assuming a spherically symmetric point source with step-function time dependence. The phase velocities are used to analyze the Rayleigh waves of the Massachusetts Mountain earthquake of 5 August 1971. Measured values of source phase for this earthquake are consistent with the focal mechanism determined from P-wave first-motion data (Fischer et al., 1972). A moment-tensor inversion of the Rayleigh-wave spectra for a 3-km-deep source gives a horizontal, least-compressive stress axis oriented N63°W and a seismic moment of 5.5 × 1022 dyne-cm. The general agreement between the results of the P-wave study of Fischer et al. (1972) and this study supports the measurements of phase velocities and, in turn, the explosion source model used to calculate φs.

KN s-wave phase shifts in the non-relativistic quark model

1995 ◽  
Vol 589 (4) ◽  
pp. 585-600 ◽  
Author(s):  
B. Silvestre-Brac ◽  
J. Leandri ◽  
J. Labarsouque
Keyword(s):  
Quark Model ◽  
Phase Shifts ◽  
Relativistic Quark Model ◽  
S Wave ◽  
Wave Phase

scholarly journals Pion Theory of Nuclear Forces and Low EnergyP-Wave Phase Shifts

1961 ◽  
Vol 25 (3) ◽  
pp. 427-435 ◽  
Author(s):  
Shoichiro Otsuki ◽  
Mituo Taketani ◽  
Ryozo Tamagaki ◽  
Wataro Watari
Keyword(s):  
Phase Shifts ◽  
Nuclear Forces ◽  
Wave Phase

Model study of explosion-generated Rayleigh waves in a half space

1964 ◽  
Vol 54 (2) ◽  
pp. 475-484
Author(s):  
I. N. Gupta ◽  
C. Kisslinger
Keyword(s):  
Rayleigh Wave ◽  
Half Space ◽  
Rayleigh Waves ◽  
Radial Component ◽  
Two Dimensional ◽  
Source Depth ◽  
Dimensional Model ◽  
Retrograde Motion ◽  
Model Study ◽  
Two Dimensional Model

ABSTRACT The Rayleigh waves generated by an explosion on or in the interior of a two-dimensional model show that the source acts as a downward impulse when the shot is on or just below the surface, and as a buried source of compression for deeper shots. The seismograms are in agreement with established theory for the line source on or in a half-space. The source depth corresponding to the reversal of polarity of the Rayleigh wave is small, and appears to be equal to the radius of the zone of inelastic failure around the shot. The polarity reversal is a true indication of a change in the mechanism of Rayleigh wave generation, and is not related to the change from retrograde motion at the free surface to prograde motion in the interior associated with the change in sign of the radial component at depth.

Statistical properties of Rayleigh waves due to scattering by topography

1967 ◽  
Vol 57 (1) ◽  
pp. 83-90
Author(s):  
J. A. Hudson ◽  
L. Knopoff
Keyword(s):  
Surface Waves ◽  
Rayleigh Waves ◽  
Seismic Noise ◽  
Forward Scattering ◽  
Statistical Properties ◽  
Body Waves ◽  
Simplified Model ◽  
Two Dimensional ◽  
Especial Reference ◽  
The Earth

abstract The two-dimensional problems of the scattering of harmonic body waves and Rayleigh waves by topographic irregularities in the surface of a simplified model of the earth are considered with especial reference to the processes of P-R, SV-R and R-R scattering. The topography is assumed to have certain statistical properties; the scattered surface waves also have describable statistical properties. The results obtained show that the maximum scattered seismic noise is in the range of wavelengths of the order of the lateral dimensions of the topography. The process SV-R is maximized over a broader band of wavelengths than the process P-R and thus the former may be more difficult to remove by selective filtering. An investigation of the process R-R shows that backscattering is much more important than forward scattering and hence topography beyond the array must be taken into account.

Sign in / Sign up

Export Citation Format

Share Document